In 1971, the present inventors established an efficient method of developing a cholesterol synthesis inhibiting agent aimed at a compound produced by a microorganism, and screening was carried out, and in 1973 found that a compound designated as ML-236B having the desired activity is produced by a microorganism of the genus Penicillium (Japanese Examined Patent Publication, Kokoku, No. 56-12114); in 1981 by a microorganism of the genus Paecilomyces (Japanese Examined Patent Publication, Kokoku, No. 59-45360; in 1982 by a microorganism of the genus Hypomycess (Japanese Examined Patent Publication, Kokoku, No. 62-19158); by a microorganism of the genus Trichoderma (Japanese Examined Patent Publication, Kokoku, No. 62-19519; and by a microorganism of the genus Eupenicillium. Attention has been paid to compounds belonging to this class as therapeutic agents for arteriosclerosis and coronary heart disease, because these compounds specifically inhibit HMG-CoA reductase and repress the synthesis of cholesterol.
Although, as stated above, the compounds belonging to this class exhibit a specific and notable therapeutic efficacy, they are relatively unstable, and therefore, difficult modification steps are necessary for the production thereof.